Hydraulic propelling mechanism



NOV. 28, 1944. E J SVENSON 2,363,707

HYDRAULIC PRGPELLING MECHANI SM Original Filed July 3C!l l952` 6 Sheets-Sheet l 52 Ermes/ JSr/rzson x 'Ey @4m Nov. 28, 1944. a J. svENsoN 2,363,707

HYDRAULIC PROPELLING MECHANISM Original Filed July 30' 1932 6 Sheets-Sheet 2 @f7 J6@ 3Q 170 174 A 282 200 j@ 16g 90 E:

J9@ l@ 36 54 66 1% 2V 21o liz/mentor Ernest ,ISU/erwan NW- 28, l944 E s svENsoN 2,363,707

HYiUf C PROPELLING MECHANISM Orglna Filed July ISOl 1932 6 Sheets-Sheet 3 L64 0 Q6 @5 J@152 166 6230 @n ini) 65 26' [06 50 78 46 112 50e 2 28 114 76 179 Ernesz'juensom NOV- 28, 1.944 E. J. svENsoN HYDRAULIC PROPELLING HECHANISH 6 Sheets-Sheet 5 Original Filed July 50' 1932 Nov. 28, .1944. E. J. svENsoN 363.707

HYDRAULIC PROPBLLIRG lEClvIAHISI riginal Filed .my so, 1932 s shuts-sneu s Patented Nov. 28, 1944 HYDRAULIC PROPELLING- MECHANISM Ernest J. Svenson, Rockford. Ill., assigner, by

mesne assignments, to Odin Corporation, Chicago, lll.. a corporation of illinois Application July 30, 1932, Serial No. 621,025 Renewed January 12, 1938 23 Claims.

This invention relates generally to hydraulic systems of control, and more particularly to hydraulic systems and apparatus adapted for use in controlling the movement of machine parts and the like.

One of the important problems confronting machine tool designers as well as users of machine tools is that of providing the desired features of control. In other words. the ease with which an operator may control the functioning of the machine as well as the simplicity of the structural arrangement of the control mechanism is of utmost importance from the standpoint of economical shop production. Heretofore, in many instances, and this is particularly true in mechanically controlled and operated machines, complicated control mechanisms, such as clutches and the like, have been employed. In such instances, rather complicated structural design has been resorted to and it is one of the primary objects of my present invention to provide a simplified system of control for machine tools and the like in which the number o! control elements ls reduced to a minimum, and the ease with which an operator may control the functioning of a machine is greatly facilitated.

My invention is more particularly applicable to hydraulic systems of control and to this end I propose to provide an improved emciently operable system wherein the use of clutches and other structures heretofore considered necessary to the efllcent functioning of the machine is eliminated.

More specifically, it is an object of my present invention to provide a hydraulic actuator system in which the mere shifting of a. control valve will serve to initiatethe operative functioning of a pumping mechanism or to render said pumping mechanism functionally inoperative without the necessity of disconnecting said mechanism from its source of power supply.

Still another object of my invention is to provide apparatus or systems of control which are particularly applicable in instances where one pump is employed for propelling a machine part at a feeding rate and another pump is employed fot' propelling said part at a rapid rate, and to this end I propose to provide means responsive to the movement of a main control valve for contrtl ing the functioning of one ot the pumps without affecting the functioning of the other pump.

St ll more specifically, my invention contemplates the provision of means shiftable in response to the slight movement of a main control valve for operatively connecting a pump. such as one of the above mentioned pumps. with an actuator, such as an actuator cylinder, and in response to further slight movement of the main valve, to automatically render said pump functionally inoperative for propelling purposes.

A further object of my invention is to provide apparatus, as above set forth, which includes an improved valve mechanism for e'ectlng the control of a hydraulic actuator system.

Still another object of my invention is to provide improved means whereby the timed movements of a plurality of hydraulic actuators may' be effectively controlled and to this end I propose to provide improved mechanism which will enable one actuator to experience a dwell of sunlcient duration to permit the continued movement of another actuator and thereby enable the simultaneous return of both actuators upon the completion of their working strokes.

Another object of my invention is to provide apparatus, as above set forth, which includes an improved unitary pumping mechanism having a plurality of pumps, the delivery of which may be simultaneously controlled, and to carry out this feature of the invention I provide a combined feed pump and charging pump structure so arranged as to enable the automatic variation in volumetric delivery of the charging pump in accordance with variations in displacement of the feed pump. In this' manner I propose to eliminate the necessity of operating a charging pump, such as a gear pump, continuously at its maximum charging rate as has been commonly done in the past, thereby eliminating by-passing of nuid which necessarily causes deleterious increases in temperature of the i'luid medium.

The foregoing and numerous other objects and advantages will be more apparent from the following detailed description when considered in connection with the accompanying drawings, wherein:

Figure l discloses a hydraulic system ot control which is representative of one embodiment of my invention Figure 1A discloses the valve member in its rapid traverse approach position;

Figure 1B discloses the valve member in its rapid reverse position;

Figure 2 discloses a modied system of control whereinv two low pressure or high displacement pumps are employed, one for charging the feed pump and the other for rapid traverse purposes, as distinguished from the system shown in Figure 1 wherein one low pressure or high displacement pump is employed;

Figure 3 is a sectional view oi' the main control valve mechanism similar to that disclosed in Figure l, with the valve of the feed pump control device shown in its central position, said view being a horizontal section taken substantially along the line 3 3 of Figure 4;

Figure 4 is a vertical sectional view of said valve mechanism taken substantially along the line 4 4 of Figure 3;

Figure 5 is a vertical sectional view of the valve mechanism taken substantially along the line l-B of Figure 4;

Figure 6 is a fragmentary horizontal sectional view of the valve mechanism taken substantially along the line 8 6 of Figure 5, said view being shown to more clearly disclose the passageway which serves to maintain communication between the opposite extremities of the valve chamber;

Figure 7 is a vertical transverse sectional view of the valve mechanism taken substantially along the line 1 1 of Figure 4;

Figure 8 is a transverse vertical section taken substantially along the line 8 8 of Figure 4;

Figure 9 is a transverse sectional view taken substantially along the line 9 8 of Figure 4;

Figure 10 is a transverse vertical sectional view taken substantially along the line lli-I0 of Figure 4;

Figure ll is a similar transverse sectional view taken along the line H H oi' Figure 4;

Figure l2 is a similar transverse section taken along the line I2 I 2 of Figure 4;

Figure 13 is a transverse section taken along the line N I of Figure 4;

Figure 14 is an enlarged detail view of the lower left-hand portion of the main control valve mechanism shown in Figure 4 to more clearly illustrate my improved means for effecting a dwell in an actuator piston prior to the shifting of the main control valve;

Figure 15 is a view similar to Figure 14 disclosing the unbalancing member shifted to its operative position;

Figure 16 is an enlarged central sectional view of one of the actuator cylinders and piston to more clearly illustrate the sealing device associated therewith;

Figure 17 is an enlarged central sectional view of the combined gear pump and plunger pump structure capable of being used in my improved system of control;

l Figure 18 is a transverse sectional view of the plunger pump section taken substantially along the line Il l of Figure 1'1;

Figure 19 is an enlarged fragmentary view of the gear pump coupled with the plunger pump, said view being taken substantially along the line i9-I9 of Figure 17;

Figure 20 is a vertical central view shown partly in elevation of a modified combined plunger pump and gear pump construction, said view differing from Figure 17 in that the plunger pump of Figure 20 is of the type equipped with a shiftable pintle for varying the pump displacement;

Figure 2l is pump of Figure an end elevational view of the 20 shown partly in section, said view being taken substantially along the line M of Figure 2i); Y

Figure 22 is a circuit diagram similar to Figure l. disclosing the shiftable control or valve members in positions illustrated in Figure 1A, directional arrows being employed to more clearly illustrate the direction of fluid flow in the various channels; and

Figure 23 is a view similar to Figure 22 disclosing the positions occupied by the slow traverse pump control element and :ne yeversiniz valve when said slow traverse pump r uid pressure generating means is operating to propel the actuators at a relatively slow speed, directional arrows being employed to more clearly illustrate the direction of fluid flow in the various conduits.

Referring now to the drawings more in detail wherein like numerals have been employed to designate similar parts throughout the various figures, it will be seen that one embodiment of my invention includes a system of hydraulic control of the type shown in Figure l. Before taking up a description of the system shown in Figure i, I wish to call attention to the fact that said system is made up of a number of important devices which I propose to designate generally by numerals so as to facilitate an understanding of the description which is to follow. My improved system includes a suitable reservoir 2l, Figure l, and a main control valve mechanism designated generally by the numeral 26. This control valve mechanism, in the disclosed embodiment, is made up of a main operating valve 29, a feed pump control mechanism 30, and a fluid balancing control device 32. A suitable rapid traverse pump 3l, preferably of the gear pump type, is shown in operative association with the valve mechanism 2B, and a feed pump or plunger pump 3B is also connected with said valve mechanism through the agency of the control mechanism 30. These pumps 34 and 3B are shown in detail in Figures 1'1 to 19 inclusive. A pair of hydraulic actuators 38 and l0 are hydraulically connected with the control valve mechanism in a manner later to be described. I have shown a rotary dog supporting plate or disk 42 mounted upon a shaft M, and this shaft M is preferably rotated in timed rela tion with the movement of one of the actuators. For a more detailed description of this dog carrying disk, reference is made to my copending application, Serial No. 582,192, filed December 21, 1931, now issued as Patent No. 2,078,697, dated April 27, 1937.

It is believed that the structural and functional characteristics of the control valve mechanism 2li, as well as the other elements of the system, will be more readily understood by describing said parts in connection with the method of operation. Consider that the pumps 34 and 38 are being driven from a suitable source of power supply, not shown, and that the main control valve 2l occupies the central position shown in Figure l. It will be seen that this operating or control valve 29 is longitudinally shiftable within a casing 4I and is adapted to be manually shifted to the right by moving a control handle lll, Figure 5.- Movement of the control handle IB rotates a vertical shaft 50 which, in turn, is connected to the right end of the valve 28, Figures 1, 3, and 4, by means of an arm 52.

The position of the valve 2B, as shown in Figures l l, 3, and 4, will hereinafter be referred to as its neutral or by-passing position, and it will be seen that when said valve occupies this position, fluid discharged from the feed pump 38 is directed through a conduit M and a conduit $6 to a port 58 which, at this instant, communicates with an annular passage B0 of a control member 92 which forms a part of mechanism previously referred to as the feed pump control mechanism Sil. Fluid entering the passage lll from the port I8 circulates through a port B4 and returns through a aaosfrov conduit IB to the intake side of the feed pump Il. Thus, the feed pump 36 is functionally inoperative with respect to either of the actuators Il or M when the control member B2 and the main control valve 2l occupy the relative positions shown in Figure 1. Likewise, should the main control valve 28 be slightly shifted to the left oi' the position shown in Figure l. the control member B2 would occupy the position shown in Figure l, and thus the feed pump 36 would be I functionally inoperative with respect to either of said actuators.

Fluid from the reservoir 2l is directed through a conduit 8B to the intake side of the rapid traverse pump 3l and is discharged from said pump through a conduit lll to an intake port l2 in the valve casing 46. 'This fluid is directed through radial passages 14, Figures 1, 4, and '7, into a longitudinal passage 16 which communicates with an end chamber 1B. This end chamber 'I8 communicates through a longitudinal passage Bil, Figures 6 to 1l inclusive, with an oppositely disposed valve chamber 82, and this valve chamber B2 communicates with the reservoir 2l through a conduit 8| and a restricted orifice 8B. Thus, when the valve parts occupy the relative positions shown in Figures l, 3, and 4, huid discharged by the rapid traverse pump 34 circulates through the valve and is returned to the reservoir, the restricted orifice 86 in this instance serving merely to maintain suiiicient iluid pressure to retain the main valve 28 in balance. In other words, the back pressure set up by the restricted orifice 86 acts against the opposite ends of the valve communicating with the chambers 18 and 88 with equal force, and hence maintains the valve memberA 2B in balance. It will be understood of course that the valve is always in balance regardless of pressure acting thereon, due to the fact that the area at each end of the valve is the same, and further, that the fluid is adapted to unrestrictedly pass to both ends of said valve. The conduits for establishing communication between the chambers 'IB and B8 for the purpose set forth above will be more clearly understood from the n detailed description of the fluid balancing control device 32, as will later appear.

Assume now that the valve member 2B is shifted to the right from the position shown in Figure i to the position shown in Figure 1A and Figure 22. This movement is accomplished by manually shifting the control lever IB so as to longitudinally move the valve member. This shifted position oi' the valve member may be referred to as a rapid approach position because at this time the system i is conditioned for imparting rapid movement to the left oi' the piston 2l* of the actuator 38 and rapid movement to the left of the piston 4B oi the actuator 40. Tracing the iluid, we find that in this rapid approach position fluid from the rapid traverse pump 3l enters the valvel port 12. passes through side passages 90 in the valve member 28 through a port!! and then through conduit N. distributor IB, and conduit 91. and then into the right end of the actuator 3B and through a conduit 9B into the right end of the actuator Il. Fluid from the left ends oi the actuators 38 and lil is returned through conduits |00 and |02 respectively to a valve port IM which now communicates with the chamber 82 and consequently with the reservoir 2| through the restricted orifice Bl. In this manner 'rapid movement to the left is experienced by each of the pistons 28'L and lll. 'I'he distributor mechanism Il serves as a compensating means which may be adjusted so as to permit the simultaneous actuation of both cylinders regardless of the fact that one may be subjected to a greater load than the other. Other devices, such as the well known rack and pinion mechanism having backlash to compensate for such variations, as shown in the American Machinist, dated August 4. 1927 (see particularly the statement in the rst paragraph on page 207), may also be used without departing from the spirit and scope of my invention. As a further explanation of what I mean by the conventional rack and pinion mechanism, reference is also made to page 479 of the American Machinist" for September 20, 1928, wherein another machine is disclosed which is equipped with a rack and pinion mechanism, and wherein this mechanism is described as being connected with each of the heads for the purpose of equalizing the movement of the heads.

It will also be apparent that upon shifting the valve member 2B to the right. a pressure is increased within the valve passages 9D, due to the restriction of the radial passages Il as they traverse their companion valve port 12. and this fluid pressurc is transmitted to a chamber |06 oi the leed pump control device through passages |08, Ilil, and H2. This causes the control member 62 to be suddenly shifted to the left, the fluid from the advancing side thereof passing outwardly through a passage l I4, which then is in communication with the return chamber B2. This causes the control member 62 to be shifted to the position shown in Figure 1A, thereby preconditioning the circuit connected with the feed pump 36 for imparting a feeding movement to the pistons 38x and lila upon the completion of the rapid approach movement of said pistons.

When the pistons 38u and Ill reach the limit of tbrir rapid approach movement, a dogr IIS on the disk 42 engages a finger H8 secured at the lower end of the stem or shaft 5D so as to automatically return the valve member 28 to a substantially central or neutral position as shown in Fig. 1 and in Fie. 23. As previously stated, the circuit, inciuding the plunger pump 36. is now conditioned for drecting fluid, under high pressure, into the rifzht end of each actuator, due to the fact that the valve port 58 is now closed by the control mcmber 62 (see particularly Fig. 23), thereby preventing free circulation of the fluid delivered to and discharged by the feed pump, as previously described. With the main valve 2li in its neutral or feeding control position the control member 62 is locked in position due to the sealing of valve passages extending between the main control valve and the control device 30. The iiuid from the gear pump now circulates or by-passes through the restricted orifice/ 86. as previously rscribed, ard fluid from the advancing ends of the pistons 38* and 40 is directed through the valve passage IM which new communicates with *he annular passage Il" oi' the control member G2 tvough a passage |20, Figure 3. Thus. the plunger pump or feed pump 36 is connected in a closed circuit with the actua-tors for propelling same at a feeding rate. and the rapid traverse pump, lay-passes through the main valve.

Attention is directed o the fact that when the passage or port 14 lv-lriits. a substantial diffe-ence in pressure is established between the chambers or passagrs 90 and 82. It is this difference in uresulre that causes the vnlve member 62 to move with a snap Quick or sudden movementy of the valve member 62 is very desirable. It should also be noted that the valve member 28 when positioned as shown in Figure 1, prevents the valve member 82 from shifting. Fluid pressure at the forward end of the actuator cylinder temporarily becomes higher than the propelling pres sure upon the completion of the piston stroke, but my improved construction precludes this sudden development of pressure from having any effect upon the valve member 82. That is to say. the valve member 82 is positively secured against shifting. It should also be noted that, when the valve is suddenly unbalanced for reversal only a slight travel of the valve will place the feeding circuit in neutral, and thereby allow a tool, such as a rotary cutter propelled by the hydraulic actuators to clean up its work on a piece of material without leaving any marks because several revolutions could be experienced before the rapid traverse fluid is put into play and the actuator returned.

We shall assume that it, is desirable to arrest the movement of the actuator piston 48 before the piston 38* completes its feeding stroke. Thus, the piston 38" continues after movement of the piston 48 has been arrested and as it approaches the limit of its advancing movement, a dog |28 moves into engagement with the right end of a valve member |28 of the iluid balancing control device 32. A valve or plunger |22. the functioning of which is adjustably controlled by an abutment screw |24. is employed to automatically establish communication between opposite sides of the piston 48*l when it approaches the position shown in Figure 16. The shifting of the valve member |28 to the left, from the position shown in Figure 14 to the position shown in Figure 15, establishes communication between the valve chamber 88 and the reservoir 24 in a manner about to be described. When thevalve member |28 occupies the position shown in Figure 14, communication between the valve chamber 88 and a conduit |38 unrestrictedly connected with the fluid reservoir 24 is broken, but when the valve member |28 is shifted to the position shown in Figure l5, fluid from the valve chamber 88 flows through a passage |32 into a valve chamber |34 which at this instant communicates with an adjustable needle valve |38 through a central valve passage |38, a radial port |48, and an annular passage |42. In this manner fluid ows from the valve chamber 88 at a speed determined by the setting of the valve |38 into a passage |44, Figure l5, an annular passage |48 of the valve member |28 and thence unrestrictedly back to the reservoir 24 through the conduit |38. The purpose of controlling the ow of iluid from the chamber 88 is to obtain a predetermined dwell or time control of the actuator pistons before rei versal is imparted thereto, as will more clearly appear as the description progresses.

In order to more clearly understand the manner in which the valve chambers 18 and 88 are in communication when the main valve member 28 occupies its central or neutral position, reference is made to Figures 1, l2, 14, and 15. As previously described, the valve chamber 88 communicates with the chamber |34 of the control device 32 through the passage or conduit |32 (see Figures 14 and 15). With the valve member |28 in the position shown in Figure 14, the chamber |34 communicates with an annular chamber |38, and this chamber |38 communicates with the longitudinal valve passage 88 (Figure 12) through a passage |81. The extremity of the valve passage 88 oppositely disposed from the point of communication with the passage |31 communicates ascavov with the valve chamber 18 (see Figure 8). Thus balanced fluid pressures exert equal force in opposed directions upon the valve member 28 so as to maintain the valve member in its central or slightly shifted position. That is to say, il' the valve member 28 is shifted slightly to the left or to the right of the position shown in Figure 1, the balanced condition of the valve member 28 remains undisturbed. It will also be noted that the valve chamber 82 is maintained in constant communication with the longitudinal passage 88 as illustrated in Figures 6 and 10.

From the foregoing it will be apparent that when the valve member |28 is shifted to the left, it ail'ects an unbalancing of the normal fluid pressure acting upon the main valve 28, thereby causing the iiuid pressure within the right chamber 18 to move the valve 28 to the left at a speed determined by the setting of the needle valve |38. When the valve member 28 has shifted sufllciently to bring an annular valve port |48 into registration with the valve passage |44, the needle valve |38 is by-passed so as to spermit the free or unrestricted fiow of fluid from the chamber 88 through longitudinal passages |88 in the valve 28 which communicate with the annular port |48 as clearly shown in Figures 14 and 15. The radial passage 14 is enlarged slightly at the surface of the valve 28 by opposite recesses 14a. As the valve 28 moves to the left from. the central position of Figures 1 and 23, communication is established between the port 12 and the port |84 before communication is cut off between the port 12 and the chamber 18 for the distance between the left side of the in-take port 12 and the right extremity of the right recess 14a of the radial port 14 is greater (as for example. in the order oi .031 of an inch) than the distance between the right side of the port |84 and the right side of the enlarged valve section which controls this port. As

the valve begins to uncover the port |84, iluld is l.

admitted to the outer end of the actuator 38 and the movement of the actuator piston 38a to the right further assures maintenance of a suilicient pressure in the chamber 18 (the port 82 opening at the same time as the port |84) to cause the valve 28 to move to its extreme rapid reverse position as shown ln Figure 1B. In this manner I am able to positively insure the sudden shifting of the valve 28 to its rapid reverse position shown in Figure 1B when the desired dwell in the actuator pistons has been experienced.

As the valve member 28 shifts to its left or rapid reverse position, fluid from the gear pump 34 within the valve passages 88 is directed through a passage |82 which communicates with passage ||4 through a connecting passage |84, thereby causing the control member 82 to be suddenly shifted to theright. Fluid from the advancing end of the control member 82 is directed through the passage ||2 into the end chamber 18 thereby penmitting free axial movement of the control member to the right. With the control member 82 in this position, the plunger pump circulates through the annular e 88, as previously described. When the pistons reach their starting position, a dog |88 engages a finger |88, Figures 1 and 5, thereby causing the valve 28 to be returned to its neutral position. It should also be noted that as the dog |28 moves away from the right end of the valve member |28, Figures l, 14, and 15. a coil spring |88 automatically returns the valve member |28 toits normal position shown in Figure 14. A pin |82 serves to limit the movement of the valve member |28 to the right.

Attention is also directed to a. vent or bleed passage |64 in the valve member 28 which serves, when said valve member 2B is in the position shown in Figures l and 3 and said control member 62 occupies the position shown in Figure 1A, to establish restricted communication between the closed fluid circuit containing the plunger pump 36 and the low pressure iluid supply. In other words, when the circuit is in feeding condition as shown in Figure 23, if there is any difference in volumetric displacement between opposite sides of the actuator pistons, this will be compensated for by the presence of the bleed passage or vent |64, and further, if there should be any slight leakage oi fluid due to the wear in the piston rods, failure of the actuator packings, etc., said vent would serve to compensate for suchfaleakage. In no sense should the presence of this vent |84 be confused with devices heretofore employed to make up" iiuid losses due to slippage of uid through pump valves, etc., which is commonly experienced in conventional uid circuits. In fact, the size of the vent |64 is so small that it will have no eilect whatsoever on pressure conditions within the closed circuit, except for such on the inlet side of the plunger pump as merely serve to compensate for slight volumetric variations, as above set forth. Attention is also directed to a similar vent or passage |66, Figures l and 3, which ix'nctions similarly to the vent |64 when the control member G2 occupies the position shown in Figures 1 and 3.

As has been previously set forth, the radial ports 14 in the valve 28 are provided at each side thereof with oppositely disposed recessed portions 14, These portions 14 serve to provide restricted communication between the discharge side of the low pressure pump 34 and the outlet passage 16 as said valve is shifted to either side oi its neutral position. In other words, as said valve shifts to one side. the restricted communication referred to above, causes an increase in pressure within the valve passages 90 which is transmitted to the control member 82 before the valve passages 90 actually register with the companion valve passages or ports 92 and |04. As previously described, the passages |52 and Illl serve to establish communication between the valve passages 90 and the control member 82 before the valve 28 actually cuts in the low pressure fluid for propelling purposes. 'I'he importance oi this structural arrangement will be apparent when it is understood that I am able to control the functioning of the closed circuit which includes the feed pump Il without aecting or changing the functioning of the low pressure circuit which includes the gear pump 34. In other words, by merely shifting the main valve 2l to the right a sumcient distance to establish communication between the valve passages Il and the passage III, Figure l, I am able to cause the control member 62 to shift to the left without actually cutting in the low pressure iiuid. Likewise, if the valve member Il is shifted slightly to the left from its neutral position so as to register the valve passages 9|! with the passage |52, the control member 62 will automatically shift to the right so as to render the closed circuit, including trol enables the starting and stopping of an actuator to be controlled independently of the rapid traverse propelling mechanism, such as the rapid traverse gear pump shown therein.

Attention is also directed to the sealing arrangement which I employ to prevent the leakage of fluid longitudinally of the actuator pistons 38' and Il (see Figure 16). It will be seen that these pistons are provided with a pair of annular recesses |61 adapted to retain a plastic or impressionable sealing medium III which may be delivered, under pressure, into the left end of the piston rod I'll through a longitudinal recess |13 which communicates with a chamber I'Il within the piston. By means of a spring pressed plunger |11 the plastic sealing medium Il! is continuously maintained under pressure. This sealing medium is preferably a compound including suitable grease. graphite and binding material. Thus, the sealing material within the annular grooves |61 serves to positively prevent the slippage or leakage of fluid from the high to the low pressure sides of the piston. It should also be noted that, while the grooves I serve to retain grease in position, grease may also nll up the space between the two piston rings, or, in other words, provide an effective grease illm, which cooperates with the annular grease sections ln the groves |81 in preventing slippage of fluid from one side of the piston to the other.

Attention is also directed to the manner in which I seal the fluid within the valve chamber 1l, Figure 5, against leakage along the shaft or stem Il. I provide said stem with a pair of annular grooves il* and connect these grooves through -passages |19 with the reservoir 2l. Thus, any uid, under pressure from the valve chamber 1B which may reach the annular grooves or recesses 60', will be directed back to the reservoir 24 and hence will not leak to the Outer ends of the stem Il. It will be seen that a psage III, Figures 5 and 7 to 10 inclusive, is provided in the valve casing 4l and this passage Ill communicotes with the passage |44 and thus serves to establish communication between the passages |19 and the fluid reservoir.

In Figure 2 I have disclosed a modiiled circuit arrangement which is designed to employ a feed pump which requires a charging pump to constantly deliver uid thereto. In this circuit of Figure 2 I employ the same valve mechanism designated generally by the numeral Il and the same nuid reservoir 24 as well as a similar rapid traverse pump I4. A feed pump Il* is shown which is continuously coupled with the discharge side of a charging pump 34s which may be similar in structural characteristics to the gear pump 34. The only difference in structural arrangement of the circuit shown in Figure 2 is that instead of connecting the plunger pump 3l* in a closed circuit which is functionally independent of any low pressure fluid, I employ the additional charging pump 34* which continuously charges the pump nl. 'I'he pump Il might be one oi' the conventional pumps now employed wherein considerable slippage of fluid is experienced,

' thereby requiring a charging pump, auch as the the feed pump 3B, functionally inoperative for Y propelling Din-.poses without cutting in the low pressure iluld. By this arrangement I am able to eliminate conventional clutch mechanism, etc., heretofore employed in many instances to control the operative functioning of iluid pumps and the like. lirthermore, my improved system of conpump 34s, to be continuously connected therewith to make up" iiuid lost as the result of said slippage.

Referring now to Figures 17 to 19 inclusive, it will be seen that one form of pumping mechanism which is capable of use in my improved system or control includes a combined plunger and gear pump device indicated generally by the numeral |88. This pumping mechanism or unit |88 is made up of the ieed or plunger pump 88 and the gear pump 214` The gear pump 84 is made up of a pair of gears |10 and |12 which are enclosed within casing sections-|14 and |18. Side plates |18 and a central casing section |80 cooperate with the casing sections |14 and |18 to provide a suitable housing for the gears |10 and |12 as clearly shown in Figure 11. Fewer is transmitted to the gear |10 from any suitable source of supply (not shown) through a drive shaft |82 which ls connected by a pin |84 to a sleeve |88 with which the gear |10 rotates as a unit. A central adjustable valve member |88 which is provided with peripheral ports |90 is adapted to receive and convey iluid from radial passages |92 within the gear |10 which is directed through said passages when the teeth oi said gear mesh with the teeth of the companion gear |12. Valve |88 may be adjusted by rotating a graduated disk |84, Figure 1'1, which operates through a pinion |98 and a quadrant |88 .meshing therewith, said quadrant being secured to the outer end of a stub shaft 200 which makes a tongue and groove connection with the valve |88, as clearly shown in Figure 1'1. When the valve |88 occupies the position shown in Figures 1'1 and 19 and the gears rotate in a direction indicated by the arrows, a portion of the iluid received by the discharge chamber 202 oi the pump is adapted to pass through the radial passages |92 to the intake chamber 204. In order to increase the uid delivery from the discharge chamber 202, it is only necessary to adjust the valve |88 in a counterclockwise direction, as viewed in Figure 19, thereby reducing the amount of fluid which is by-passed from the high to the low pressure chambers. In fact, the valve can be so adjusted that no fluid is by-passed from the chamber 202 to the chamber 204 and in this position the pump is operating at its maximum delivery. When the pumping unit |88 is employed in the system shown in Figure 1, fluid passes into the gear pump chamber 204 fromthe conduit 80 and ls delivered from the discharge chamber 202 through the conduit 10 which'cpnnects with the main control valve mechanism.

The plunger pump 38 includes a plurality oi radially reciprocable pistons or plungers 208 which are successively urged outwardly to deliver fluid at high pressure from the chambers at the outer ends of said pistons through the agency of an adjustable eccentric driving ring 208.` A tapered valve 2I0 is employed to control the ow of fluid toward and away from the outer ends of the pump pistons 208. Fluid received by the plunger pump from the conduit 8 8 enters the chamber 2|2 and is successively directed by a peripheral poriI 2|4 to the pistons which are experiencing an intake stroke. A valve port 2I8 receives huid under high pressure and directs the same to the discharge conduit 84.

The eccentricity oi the driving ring 208 is occasioned in response to manual manipulation ot the graduated adjusting disk |80.` Turning of this disk causes a member 2|8 to shift longitudinally within a driving sleeve 220, and the inner end oi' this member 2|8, through the agency of an inclined projection 222, is lcoupled with a laterally adjustable driving member 224 which, at its right end, Figure 1'1, supports the driving ring 208 with anti-friction bearings. Thus, by urging the member 2|8 to the left. within the driving sleeve 220, the driving member 224 is shifted laterally or upwardly. as seen in Figure 11. therebilrr varying the eccentriclty oi the driving ring 208. For a more detailed disclosure of the tapered valve arrangement disclosed in Figure 17, refer ence is made to Figure 25 of my Patent 2,078,697, the application for which was iiled December 2l, i931, and Figure 4 of my Patent 2,036,162, thel application for which was led September 13; 1930.

From the foregoing it will be apparent that by a single adjustment oi the graduated disk |94, the delivery ci the gear pump, as well as the displacement of the plunger pump, will be simultaneously varied. This arrangement is such that in instances where the gear pump might be employed to charge the plunger pump, an increase in displacement of the plunger pump occasioned by movement of the member |94 would automatically eilect an increase in volumetric delivV ery of the gear pump to the plunger pump. In many systems oi control of the conventional type, wherein gear pumps are employed to charge plunger pumps, the gear pumps are continuously operated at maximum charging rate which is usually in excess of that required by the plunger pumps, and in order to take care of excess fluid not required for charging purposes, relief valves must be employed. I propose to provide a pumping mechanism wherein the volumetric discharge of fluid ofthe gear pump may be controlled in accordance with the needs or requirements of the plunger pump. In this way increases in fluid temperatures resulting from by-passing iiuid when relief valves and the like are employed, is eliminated. f

In Figure l I have shown a system wherein the plunger pump need not be charged by the gear pump during its functioning in the closed circuit, whereas in Figure 2 I have shown a circuit arrangement wherein the gear pump or charging pump is continuously connected with the plunger pump. Thus in Figure 2 a plunger pump and charging pump unit simulating that shown in Figures 17 to 19 inclusive may be employed. In

describing the system shown in Figure 2 I stated that the gear pump 34* will serve to take care oi' fluid leakage within the pump 88' and wish to call attention to the fact that when a pumping unit, such as that disclosed in Figures 1'7 to 19 inclusive is employed. the problem of uid slippage within the plunger pump is eliminated by the presence of the tapered valve 2 Iii.` jAillm oi oil is maintained along the peripheral surface of' the tapered valve 2|0. This nlm serves as a nuid seal. Due to the tapered peripheral surface,A

there is a tendency during the rotationv oi the valve for the film to slowly migrate toward the larger extremity oi the valve, However, this slow migration of iiuid must be clearly distinguished from the deleterious effects which have heretofore been experienced in connection with the use of pumps equipped with` cylindrical valves or pintles. In these'latter devices the leakage of fluid along the peripheralsui'i'ace 'of the cylindri cal valve member not onlyresults in the loss ol fluid, but also in theevelopment oi' high temperatures. vEven though the uid nlm along, my tapered valve may slowly migrate toward the larger end thereof. this duid eventually reaches the groovesshown toward the left end ot the valve, and from. this point is conducted back to the system.

The above mentioned migration of theiluid must be clearly` distinguished from what is commonly referred to trol for machine tools and the like as uuid slippage. That is to sa?. fluid slippage usually implies a certain amount of power loss due to the slippage of fluid through a restricted area or oriiice. If the word "slip were employed to describe the slow migration of fluid along my valve, such a use of the term should not imply fluid slippage as I have referred to above. In fact, by employing the tapered valve construction disclosed herein I am able to connect the pump in a closed circuit with the actuator and thereby cause iiuid on opposite sides of the actuator to be moved as a confined body or unit. That is to say, there is an absence of slippage inasmuch as the two uid bodies or units are maintained intact.

In Figures 20 and 211 have shown a pumping unit designated generally by the numeral |68l which is of the type wherein the plunger pump is of such a construction as to require the continuous delivery thereto of charging fluid in order to take care of fluid slippage. This unit 168 is the type of unit specifically referred to in connection with Figure 2. This unit IBB* includes a plunger pump 36* which is similar in structural and functional characteristics to the plunger pump shown in the Ferris Patent No. 1,753,562, and employs a rotary driver 226 for imparting reciprocation to a plurality of radial pistons or plungers 228. A cylinder barrel 231| is carried by a laterally adjustable pintle 232 equipped with valve ports 234 and 236 which are adapted to control the flow of fluid toward and away from the pistons 228. Fluid from the plunger pump is taken in by a conduit 238 and is discharged, under high pressure, through a conduit 24B. This conduit 233 connects with the discharge chamber 242 of the gear pump indicated generally by the numeral 33a. This gear pump is similar in structural and functional characteristics to the gear pump 3l previously described in connection with Figures 17 to 19 inclusive and includes a pair of gears and i12". The gear Illia is driven by a shaft 2 which also serves as the drive shaft for the plunger pump driver 22|. Fluid is directed to the intake chamber 2 of the gear pump 3l", Figure 21, from a conduit or pipe line 24B which connects with a reservoir 250, Figure 20. A valve HiBa similar to the valve lll of the gear pump 3l, is adapted to be adjusted by manual manipulation of a handle 232 keyed to a shaft or stem 253. This shaft carries a pinion 23B which meshes with a quadrant 253 connected with the valve |33 and said shaft 23| also serves, at its right extremity, to adjustably control the displacement of the plunger pump 33. Thus, when the handle 252 is shifted to increase theidisplacement of the plunger pump 33, the valve |33* of the gear pump simultaneously shifts so as to increase volumetric delivery thereof. manner, as described in connection with the pump unit I, the volumetric discharge of the gear pump is controlled in accordance with the needs of the plunger pump. The main difference in functional characteristics between the pump units |33 and |83* resides in the fact that the plunger pump Il* of the unit |33* is of the type which normally experiences considerable fluid slippage along the cylindrical pintle or valve 232 and therefore the gear pump must be set at a rate of nuid delivery which will take care of this leakage. The pump unit |33, on the other hand. is of such a construction that the gear pump need only be set for the amount of fluid which is actually discharged by the plunger pump. taking into Inthls` consideration, of course, any slight leakage which might be experienced due to normal wear in the parts or deterioration of the valve packings. The units |68 and ISU* each employ the principle of the simultaneous control of the feed pump displacement and the charging pump delivery. It will, of course, be understood that when a system, such as that disclosed in Figure l, is employed, the plunger pump and gear pump may be operated independently as distinguished from the interlocked pump arrangement shown in Figures 1'7 to 21 inclusive.

I have endeavored in the foregoing description and in the drawings to set forth the novel features of control embodied in the present invention, which distinguish from other hydraulic propelling devices and controls in use prior to this invention. However, the functional characteristics of hydraulic circuits, when in actual operation, are diiilcult to visualize, even though the description of the various parts is fully set forth. In considering the functional characteristics of the invention, as hereinbefore described. attention is directed to the fact that the hydraulic actuator, such as the actuator structure 38, must not only shift to propel a machine part, but even more important, the iiuid must be delivered to the actuator in such a manner as to maintain a definite speed relation between the actuator and the volumetric delivery of fluid thereto. In conventional mechanical structures "backlash" is present, which may be caused by required clearance and wear of the parts. Ihe present invention enables complete elimination of "backlash" because the volumetric delivery of fluid to the actuator is controlled and maintained exactly in accordance with the required speed of travel of the actuator irrespective of load conditions.

During rapid traverse movement, fluid is drawn from the reservoir 24 and delivered through either conduit 94 or conduit I to the actuator 38. 'Ihe valve member 23 also serves to return the fluid flow from the actuator 38 to the reservoir through the pipe line 33. The orifice Il causes a restricted ow of fluid and thereby maintains the system under pressure. When the valve member 28 is shifted to the left or to the right, fluid is dispatched to the actuator 38 and presents openings of equal size in both the forward and the return ends, thereby presenting a control both to and from the actuator. This feature is particularly important when considered in connection with the cutting-cil' of the rapid traverse pump, because under such circumstances a positive control of the fluid i'iow both to and from the actuator positively and accurately synchronizes the speed of valve and actuator movement., It will be noted that when the feed pump 33 is functionally operative, it is coupled in series with the actuator 33. There are no relief valves functionally operable during this feeding movement, and the vent l does not change the closed circuit functioning during said feeding action. As previously set forth herein, this vent is so small that it does not preclude movement of fluid as a unit from the discharge side of the pump to the intake side of the actuator and from the discharge side of the actuator to the intake side of the pump. In other words, a truly closed circuit arrangement is maintained during the feeding action.

The above described valve means also serves to instantaneously enect the change in speed of the actuator. In other words. there is no time element between the change from one speed to another, as is common among conventional hydraulic systems of control. The fact that the ports or iiuid conducting passages, extending between the chamber of the valve member 2B and the chamber of the control member 62, are so short precludes any time lag in shifting from one speed to another, for example, in shifting from rapid traverse to feed. In fact this positive and accurate control, accomplished when the valves are'shifted from one position to another, constitutes a distinct advancement over conventional systems with which I am familiar.

Attention is directed to the fact that the con trol device 32 includes a speed or time control mechanism, namely, the needle valve |38 and also1 a control determinative or member |28, said control determinative being adapted to be engaged by the dogs or control abutments on the rotary control member l2. Thus the time or speed control valve |3B allows fluid to be slowly removed from the chamber 88 in accordance with the setting of the valve. Fluid channels |52-I5I (Figure 3) when the valve member 28 has been moved a sufficient distance to the left, permit the control member 62 to be shifted to the right under fluid pressure, thereby rendering the leed pump 3 functionally inoperative. Following this a predetermined dwell takes place which is of suiiicient duration--for example, to permit a cleanup cut to be taken by a cutting tool in instances where the hydraulic circuit and control disclosed herein are embodied in a machine tool,

When the valve member 28 has shifted so as to move the port |50 into communication with the conduit |44, sudden shifting of the valve 28 to its reverse position takes place, and the actuator is caused to move in a reverse direction at a rapid rate. The pressure, namely, the pressure developed by the feed pump 3l, is relieved before the fluid motor or actuator is reversed. This is of the utmost importance in connection with the proper functioning of the hydraulic system. In conventional devices prior to the present invention where a dwell is required, the pressure has not been relieved in the manner disclosed herein. It will be apparent, therefore, that the control mechanism disclosed herein provides a very practical and satisfactorily operable arrangement for hydraulic actuator systems.

Obviously the invention is not limited to the specific disclosures herein, but is capable of other modifications and changes without departing from the spirit and scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. In a hydraulic actuator system, an actuator for propelling machine parts and the like, slow traverse pump mechanism for delivering uid to said actuator at a relatively slow rate to propel said actuator at a relatively slow rate, rapid traverse pump means for propelling said actuator at a faster rate, shiftable valve means within a housing, a uid circuit including said rapid traverse pump means, said valve means and said actuator, said valve means in one position serving to render said rapid traverse pump means eilective to actuate said actuator and in another position to render said rapid traverse pump means ineffective to actuate said actuator, two-position shiftabie control means in one position renderins said slow traverse pump mechanism eifective to actuate said actuator and in the other position Il ineffective to actuate said actuator, and means for shifting said control means as an incident to the shifting of said valve means a distance insufficient to render said rapid traverse pump means eiIective to actuate said actuator.

2. In a hydraulic actuator system, an actuator for propelling machine parts and the like, slow traverse pump mechanism for delivering fluid to said actuator at a relatively slow rate, rapid traverse pump mechanism for delivering fluid to said actuator at a faster rate, a shiftable operating valve for controlling the flow o! fluid from said rapid traverse pump mechanism to said actuator, fluid pressure actuated control means operable in one position to render said slow traverse pump mechanism effective to propel said actuator and in a second position to short circuit said slow traverse pump mechanism to render it ineffective to propel said actuator, and means for supplying fluid to said control means under the control of said valve to shift said control means to said short circuit position when said operating valve connects said rapid traverse pump mechanism with said actuator for propelling purposes.

3. A hydraulic actuator system including an actuator, a power driven relatively slow delivery pump for delivering uid to said actuator at a uniform slow rate, means connecting said slow delivery pump in a closed circuit with said actuator for rendering said slow delivery pump eilective to actuate said actuator at the slow rate, a power driven rapid traverse pump for delivering duid to said actuator at a relatively rapid rate, a reversing valve having a shiftable control member, said valve having passages for directing uid from said rapid traverse pump selectively to either side of said actuator under the control of said member and passages through which fluid flows during shifting of said valve member in one direction, and control means including means operable by fluid flowing through the last mentioned passages of the reversing valve during the shifting of said reversing valve control member in said one direction to render said slow delivery pump ineffective to actuate said actuator.

4. A hydraulic actuator system including an actuator, a slow traverse pump for delivering fluid at a. relatively slow rate to said actuator, s. rapid traverse pump for delivering fluid at a faster rate to said actuator, shiftable valve means for selectively controlling the iiuid connection of at least one of said pumps with said actuator for propelling purposes, means associated with said valve means and operable in a given shifted position thereof to restrict fluid ilow from one of said pumps whereby to increase fluid pressure within said valve means for control purposes, and shlft able control means operable as an incident to the aforesaid increase in pressure within said valve means for controlling the actuation of the actuator by the other of said pumps.

5. In a hydraulic actuator system, a reciprocable actuator, a pump for delivering propelling fluid to said actuator, a valve member shiftable to a plurality of positions for controlling the direction of uid ow to said actuator from said pump, said valve member being normally balanced by fluid pressure, and mechanism shiftable in response to the movement of said actuator in one direction for causing momentary unbalancing of fluid pressure acting upon said valve member for sluiting purposes and including means for causing a predetermined dwell of said actuator before the actuator moves in a reverse direction.

6. In a hydraulic actuator system.V a reciprocable actuator, a pump for delivering propelling fluid to said actuator, a valve member shiftable to a plurality of positions for controlling the direction of fluid iiow to said actuator from said pump, said valve member being normally balanced by fluid pressure, and mechanism shiftable in response to the movement of said actuator in one direction for causing momentary unbalancing of fluid pressure acting upon said valve member for shifting purposes and including means for causing an initial retardation in the shifting of said valve and a subsequent sudden shifting thereof, whereby to enable said actuator to experience a predetermined dwell and the valve member to experience complete shifting before the actuator moves in a reverse direction.

7. In a hydraulic actuator system, a reciprocable actuator, a pump for delivering propelling fluid to said actuator, a valve member shiftable to a plurality of positions for controlling the direction of fluid flow to said actuator from said pump, said valve meinberbeing normally balanced by fluid pressure, and mechanism shiftable in response to the movement of said actuator in one direction for causing momentary .unbalancing of fluid pressure acting upon said valve member for shifting purposes and including an adjustable bleed passage connected with said valve for controlling the rate of flow of balancing fluid from the vicinity of said valve member and thereby govern the period of dwell of the actuator before said actuator moves in a reverse direction.

8. In a hydraulic actuator system, an actuator, a variable displacement feed pump connected to said actuator to supply duid to said. actuator atl rates ,determined by the rate of displacement of fluid by said pump, a variable delivery pump connected to said feed pump to supDIy charging fluid to said feed pump. and mechanical coupling means for simultaneously and proportionally varying the delivery of both said pumps.

9. In a hydraulic actuator system, an actuator, a variable displacement feed pump for delivering fluid to said actuator at a relatively slow rate, a variable delivery charging pump hydraulically connectable with said feed pump, and mechanical coupling means for simultaneously varying the delivery of both pumps, whereby the charging pump will vary its volumetric delivery in accordance with the rate at which fluid is displaced by the feed pump.

10. In a hydraulic actuator system for moving machine parts and the like, a fluid motor, a rst pump for supplying duid at a rapid rate to said motor. a second pump for supplying duid at a slower rate to said motor, a fluid circuit including a control valve connecting one of said pumps to said motor to impart movement to said-motor. said valve including a shiftable member and means cooperating with said member to restrict fluid flow in said circuit during movement of the member whereby to establish a momentary increase in pressure in said circuit, and duid actuated means operably connected to said circuit for operation at said increased pressure to control the flow of fluid from said other pump to said il. In a hydraulic actuator system for propelling machine parts and the like, a hydraulic actuator, a rapid traverse fluid circuit including pumping means for delivering fluid at a relatively rapid rate to said actuator, arelatively slow traverse uid circuit including pumping means for delivering duid at a relatively slow rate to shiftable piston type valve member for controlling the direction of fluid delivery from said rapid traverse pumping means to said actuator and for causing pressure variations in fluid flowing through said valve mechanism, said valve mechanism also including a shiftable piston type valve member shiftable independently of said first mentioned valve member rendering said slow traverse pumping means selectively effective or ineffective to supply fluid to said actuator through said slow traverse duid circuit, said independently shiftable valve member being operable in response to the aforesaid pressure variations in the fluid owing through said valve mechanism.

12. A system of hydraulic control including a hydraulic actuator. slow traverse pumping means for delivering duid at a relatively slow rate to said actuator to actuate said actuator at a relatively slow rate, rapid traverse pumping means for delivering fluid at a relatively rapid rate to said actuator to actuate said actuator at a relatively rapid rate, and control valve mechanism including a shiftable valve member for controlling the direction of fluid delivered to said actuator from said rapid traverse pumping means and another shiftable valve member for selectively rendering the slow traverse pumping means effective or ineffective to actuate said actuator, one of said valve members having means for developing variations in pressure of fluid flowing through said valve mechanism and the other of said valve members being shiftable in response to said pressure variations.

13. In a hydraulic actuator system, a recipro-` cable hydraulic actuator. fluid pressure generating means for delivering duid under pressure to said actuator at one rate, a duid circuit including said fluid pressure generating means and a reversing valve means for controlling the direction of duid delivery to said actuator from said duid pressure generating means, a second fluid pressure generating means for delivering fluid under pressure at a different rate to said actuator, two-position control means in one position rendering said second fluid pressure generating means ineffective to actuate said actuator and operable in response to the shifting of said reversing valve means to render said second fluid pressure generating means eiiective to actuate said actuator. said control means comprising a cylinder and piston, said reversing valve means including a shiftable valve member, passages controlled by said member for connecting said cylinder on opposite sides of said piston to the fluid circuit of the rst iluid pressure generating means, and means cooperating with said shiftable valve member to establish a momentary increase in the pressure of fluid transmitted through said passages to one side of said piston to shift said control means as the reversing valve member is shifted in one direction prevent shifting of said control means as the rek versing valve member is shifted in the opposite direction. 4 -y A 14. In a hydraulic actuator system, a reciprocable actuator, fluid pressure generating means for directing fluid under pressure to said actuator at a given rate, shiftable reversing valve means for controlling the direction of fluid now to said actuator from said duid pressure generating means, a second uid pressure generating means for delivering iluid to said actuator at a different frate. two-position shlftable control means in one position rendering said second fluid pressure generating means ineffective to actuate said actuator said actuator, and valve mechanism includingl a ill andoperable in response to the shifting of said valve means to render the second duid pressure generating means effective to actuate said actuator, said valve means having a fluid replenishing vent hydraulically in communication with said first and second duid pressure generating means, and channe1 means hydraulically coupling said first iiuid pressure generating means and said reversing valve means lor supplying duid to the reversing valve means to maintain said reversing valve means hydraulically in balance.

15. In a hydraulic actuator system, a reciprocable actuator, a drst pump for supplying duid under pressure to said actuator at a given rate, a duid circuit including a reversing valve connecting said pump to said actuator, said valve comprising a housing and a shiftable valvemember in said housing, said housing having duid ports controlled by said valve member to control the direction of fluid dow to said actuator, a second pump for supplying duid to said actuator at a diderent rate, hydraulically shlftable control means for selectively rendering said second pump edective or inedective to supply duid to said actuator, duid conducting means hydraulically coupling said control means with said reversing valve for operating said control means in response to movement o! said shiftable reversing valve member in a given direction to render said second pump edective to supply duid to said actuator, and means including a duid replenlshing vent in said reversing valve establishing communication between the drst pump and the second pump when said second pump is rendered eii'ective to supply fluid to the actuator.

18. In a hydraulic actuator system. an actuator, a rst duid pressure generating means lor supplylng duid to said actuator at a given rate. a duid circuit including said pressure generating means and said actuator, a control valve in said circuit, said controll valve controlling the connection ot said pressure generating means to said actuator. said valve comprising a housing and a shiitable valve plunger. said housing having an outlet port through which the duid in said circuit dows and a chamber from which substantially unrestricted communication is established to said port when said plunger is in one position, said plunger being constructed to restrict. communication between said port and chamber when the valve plunger is shifted to a second position to increase the pressure o! duid in said chamber. a second duid pressure generating means for supplying duid to said actuator at a different rate, two-position duid actuated means in one position rendering said second duid pressure generating means ineiIective to supply duid to said actuator and in the other position rendering said second duid pressure generating means ed'ective to supply duid to said actuator; and means for supplying duid from said chamber or the control valve housing to said duid actuated means to move said means from one oi its said positions to the other of its said po sitions when said valve plunger is moved to its said second position.

17. In a hydraulic actuator system comprising a duid motor for imparting movement to a member at different speeds, a first circuit for supplyingduidtosaidmctoratahighratetoimparta high speed to the member, a second circuit for supplying duid to said motor at a lower rate to impart a lower speed to the member, and valve means governing the rate at which fluid is supplied to said m to determine the speed of movement of the member. said valve means being operable to render one o! said circuits eeiftive or ineffective, selectively, to supply fluid to th# motor, and said valve means including means for varying the pressure of the duid in said one circuit and means responsive to said variation in pressure for rendering said other circuit eiIective or ineffective, selectively, to supply fluid to said motor.

i8. A hydraulic actuator system comprising a hydraulic motor, a first means for supplying duid to said motor at a high rate to impart a rapid traverse movement to the motor, a second means for supplying duid to said motor at a lower rate to impart a slow traverse movement to the motor, a first control means having one position o! ad- Justinent rendering said drst fluid supplying means ineiective to supply duid to the motor, and a secondfposition of adjustment rendering said first duid supplying means effective to supply duid to saidmotor, a second control means having one positiorrptadiustment rendering said second duid supplying means inedective to supply fluid to the motor,`and a second position of adjustment rendering said second duid supplying means eilective to supply fluid to the motor and means cooperating with said first control means and said second control means for operating said second control means when said first control means is shifted partially from one oi its said positions o! adjustment toward the other oi.' its said positions of adjustment to move the second control means from one of its positions of adjustment to its other position of adjustment.

19. In a hydraulic actuator system comprising a hydraulic motor, a rst means for supplying duid `to said motor at a relatively slow rate to impart a slow traverse movement to the motor, a second means for supplying duid to said motor at a higher rate to impart a rapid traverse movement to the motor, a drst control means having one position of adjustment rendering said rst duid supplying means edective to supply duid to the motor and a second position of adjustment rendering said drst duid supplying means ineffectlve to supply fluid to the motor, a, second control means having three positlons of adjustment. in one of which it renders said second duid supplying means ed'ective to supply duid to the motor, and in the second oi which it renders the second control means inedective to supply duid to the motor, and means cooperating with said second control means when in its third position oi' adjustment to move the first control means from one oi' its positions of adjustment to its other position of adjustment.

20. A' hydraulic system comprising a hydraulic motor, a drst means tor supplying duid to said motor at a high rate to impart a rapid traverse movement to the motor, a second means for supplying duid to said motor at a lower rate to impart a slow traverse movement to the motor, duid actuated means movable to two positions. in one o! which it renders said second -means edective to supply duid to the motor, and in the other of which it renders said second means inedective to supply duid to'the motor, and a control governing the supply of duid to said motor adjustment rendering said drst means inedective to supply duid to the motor, and other selective positions of adjustment directing duid to said duid actuated means to operate said duid actuated means to one or the other of its said two positions.

.una

said am means and having; first position of iustment rendering said first means edective Ito supply duid to the motor, a second position of selectively, while rendering said iirst means ineffective to supply iiuid to the motor.

' 21. In a hydraulic system, a iirst duid circuit including a iuid motor and a first source of fluid under pressure, a second fluid circuit including said iiuid motor and a second source of fluid under pressure. a two-position control valve in said first circuit fpr rendering the first circuit eective or ineiective. selectively, to supply iiuid to said motor, said valve comprising a housing and a shiftable valve plunger, said housing having an outlet port and a chamber from which substantially unrestricted communication is established to said port when said plunger is in one position, said chamber being in communication with said nrst source, said plunger being constructed to restrict communication between said port and chamber when the rplunger is shifted to a second position to increase the pressure of uid in said chamber, fluid actuated control means responsive to a differential in pressure between said chamber and port to control the flow of iiuid in the second circuit from said second source to said motor, and means i'or supplying iluid from the iirst source to said control means at the pressure of the fiuid in said chamber, and exhausting fluid from said control means at the pressure of the duid in said port.

22. In a hydraulic actuator system, a fluid motor, iiuid pressure generating means for supplying uuid to said motor to actuate said motor. a fluid circuit including a control valve connecting said fluid pressure generating means to said motor. said control valve including o, housing and a valve member shiitable therein from o. first position to a second position to control the flow of iluid trom said pressure generating means to said motor. said housing having a pair of chambers therein for receiving uuid, said shiitable valve member having opposing surfaces. one of which is subject to the pressure of the fluid in one chamber and the other of which is subject to the pressure of the fluid in the other chamber, means for supplying fluid from said pressure generating means to both or said chambers at equal pressure when the shiftable valve member is in one position for' maintaining the valve member hydraulically in balance, means for shifting said valve member from the first position to the second position, said means including instrumentalities for rendering the means for supplying fluid to the chambers ineffective to supply uid to one of said chambers while continuing the supply of fluid to the other of said chambers, and means for discharging the fluid from said one chamber at a predetermined rate to permit and time the movement of said valve member to the second position under the action or the fluid supplied to the other chamber.

23. In a hydraulic actuator system, a iuid motor, a first pump for supplying fluid at a rapid rate to said motor, a second pump for supplying fluid at, a slower rate to said motor, iluid actuated control means reversely operable to render said second pump eiective or ineective, selectively. to supply iluid to the motor, a rapid traverse fluid circuit including a control valve through which the fluid ilows toward the motor at the rapid rate from the ilrst pump, said control valve having a first adjustment rendering said rst -pump eiective to supply duid to the motor to drive the motor in one direction, and a second adiustment rendering said nrst pump etlective to supply iiuld to the motor to drive the motor in an opposite direction, and means to supply duid from said rapid traverse circuit under the control of said valve to said fluid actuated control means to 1mpart movement thereto in one direction or in an opposite direction, selectively, upon selective adiustment of the rapid traverse control valve from the first position ot adjustment toward the second 40 position of adJustment, and reversely.

ERNEST J. SVENSON'.

CERTIFI GATE 0F CORREO TI 0N Patent No. 2,565,707

ERNEST J November 1914.14..

SVENSON..

It is hereby certified that errorlappears 1n the printed specification ofthe above numbered patent requiring correction as follows: Page 5, second column, line 29, for "groves" read groovos page 9, second column,

line 8, claim 11, after "member" insert "for-g and that the said Letters Patent should be'read with. this correction therein that the same may conform to the record of thee-case 1n the Patent Office.

signed museale@ this 29m day of. nay, A. D. 19li5.

(Seal) Leslie Frazer Acting Commissioner of'Patonts.

selectively, while rendering said iirst means ineffective to supply iiuid to the motor.

' 21. In a hydraulic system, a iirst duid circuit including a iuid motor and a first source of fluid under pressure, a second fluid circuit including said iiuid motor and a second source of fluid under pressure. a two-position control valve in said first circuit fpr rendering the first circuit eective or ineiective. selectively, to supply iiuid to said motor, said valve comprising a housing and a shiftable valve plunger, said housing having an outlet port and a chamber from which substantially unrestricted communication is established to said port when said plunger is in one position, said chamber being in communication with said nrst source, said plunger being constructed to restrict communication between said port and chamber when the rplunger is shifted to a second position to increase the pressure of uid in said chamber, fluid actuated control means responsive to a differential in pressure between said chamber and port to control the flow of iiuid in the second circuit from said second source to said motor, and means i'or supplying iluid from the iirst source to said control means at the pressure of the fiuid in said chamber, and exhausting fluid from said control means at the pressure of the duid in said port.

22. In a hydraulic actuator system, a fluid motor, iiuid pressure generating means for supplying uuid to said motor to actuate said motor. a fluid circuit including a control valve connecting said fluid pressure generating means to said motor. said control valve including o, housing and a valve member shiitable therein from o. first position to a second position to control the flow of iluid trom said pressure generating means to said motor. said housing having a pair of chambers therein for receiving uuid, said shiitable valve member having opposing surfaces. one of which is subject to the pressure of the fluid in one chamber and the other of which is subject to the pressure of the fluid in the other chamber, means for supplying fluid from said pressure generating means to both or said chambers at equal pressure when the shiftable valve member is in one position for' maintaining the valve member hydraulically in balance, means for shifting said valve member from the first position to the second position, said means including instrumentalities for rendering the means for supplying fluid to the chambers ineffective to supply uid to one of said chambers while continuing the supply of fluid to the other of said chambers, and means for discharging the fluid from said one chamber at a predetermined rate to permit and time the movement of said valve member to the second position under the action or the fluid supplied to the other chamber.

23. In a hydraulic actuator system, a iuid motor, a first pump for supplying fluid at a rapid rate to said motor, a second pump for supplying fluid at, a slower rate to said motor, iluid actuated control means reversely operable to render said second pump eiective or ineective, selectively. to supply iluid to the motor, a rapid traverse fluid circuit including a control valve through which the fluid ilows toward the motor at the rapid rate from the ilrst pump, said control valve having a first adjustment rendering said rst -pump eiective to supply duid to the motor to drive the motor in one direction, and a second adiustment rendering said nrst pump etlective to supply iiuld to the motor to drive the motor in an opposite direction, and means to supply duid from said rapid traverse circuit under the control of said valve to said fluid actuated control means to 1mpart movement thereto in one direction or in an opposite direction, selectively, upon selective adiustment of the rapid traverse control valve from the first position ot adjustment toward the second 40 position of adJustment, and reversely.

ERNEST J. SVENSON'.

CERTIFI GATE 0F CORREO TI 0N Patent No. 2,565,707

ERNEST J November 1914.14..

SVENSON..

It is hereby certified that errorlappears 1n the printed specification ofthe above numbered patent requiring correction as follows: Page 5, second column, line 29, for "groves" read groovos page 9, second column,

line 8, claim 11, after "member" insert "for-g and that the said Letters Patent should be'read with. this correction therein that the same may conform to the record of thee-case 1n the Patent Office.

signed museale@ this 29m day of. nay, A. D. 19li5.

(Seal) Leslie Frazer Acting Commissioner of'Patonts. 

